Electrical heating means



Nov. 25, 194 7.

E. J. RlES ELECTRICAL HETING MEANS Filed sept. 1e, 1944 s sheet-sheet 1 EQJ. Rn-:s

ELECTRICAL HEATING MEANS Nov. 25, 1947.

Filed Sept. 16, 1944 5 Sheets-Sheet 2 f, 1 V ENTOR. Merit/TE@ l -MME J .nl Il rlffllan Nov. 25," 1947.

E. J. RlEs l 2,431,620

ELECTRICAL HEATING MEANS Filed Sept. 16, 1944 5 SheetS-Sheel' 5 INVENTOR BY p,

Patented Nov. 25, 12947 vUNI-TED STATES PATENT YEO'FFICIEI Company, Inc., Roche of Delaware ster, N. Y., a corporation Y Application `September 16, 1944, Serial No.' 554,395

14 Claims.

This invention relates to electrical heating means adapted f or use in units of relatively small size, such as commonly employed, for instance, by dental and medical practitioners for heating their voperating instruments and working materials.

One object of the'invention is to provide such a heating unit in a more eicient, economical and convenient form of construction.

Another object is to provide an electrical heatingy unit for replacing the gas burners which have been commonly supplied in connection with equipment employed inthe dental and medical professions.

Another object is to provide an electrical heat'- ing unit of the nature described capable of being conveniently operated to rapidly .produce an effective source of heat. l l A Vfurther object is to provide such a unit adapted to be conveniently energized by the mere pressure, against its heating portion, of the instruvment or material container to be heated, .while held in the hand of the operator, so as to obviate separate operation of the unit andl leave the operators other hand free for other work.

A further object is to provide a heating unit, operated as described above by the mere pressure thereagainst of the instrument or container to be. heated, so that the operation of the unit is `economically limited to .the desired heating Yperiod.

Still a further object is the provision of such a unit in a construction capable of being readily and economically manufactured and of being conveniently taken apart and reassembled for cleaning and repair in course of use.

To these and other ends the invention resides in certain improvements and combinations of parts, all as will be hereinafter more fully described, the novel features being pointed out in the claims at the end of the speciiication.

In the drawings:

Fig. 1 is a side elevation of portions of a supporting arm of a dental equipment stand having mounted thereon an electrical heating unit embodying the present invention;

Fig, 2 is an enlarged, sectional elevation, partly broken away, substantially on the line 20L- 2a in Fig. 6;

Fig. 3 is a plan view, partly broken away and partly in section on the line S11-3a in Fig, 2;

Fig. 4 is an enlarged elevational view of a switch detail, partly in section, substantially on the line 4er-4a in Fig. 3;

Fig. 5 is an enlarged elevation of switch details,

partly-in sectiomsub'stantially on the line *5w-5a in- Fig. 3;

form-of the device, `and lggFig. 12-is `a diag-ram of .theelectrical circuit employed in the modicationof Fig. 12.

Inthe embodiment ofthe .invention at.present preferred and-herein-disclosed by vway ofillustration, the .inventionis appliedtouse on va dental equipment stand, of any known orsuitable variety, in place ofrvtheBunsengasburner commonly employed on such stands. Referring ,more particularly tothe drawingsy there Vis shown at l2li `(Fig. v1) an equipment supporting arm extend'- ingfupwardly from thebody or ypedestal of .the standinotshowm and having pivotally mounted thereon a horizontally swinging arm 2|y carrying the instrument table and the .presentheating unit. As bestashownin Fig. v6, the arm 2l haslxed in its outer. end. avtrunnion 22, on. which is .pivotally mounted the usual swinging arm .23 carrying the instrument-table 24.

The -arm 2l, on its. underside, has.` a longitudinal4 channe1-likerecess 25, in which arelioused a sourceof air under. pressure in the Aform of an airpipe 26fand .a source .of electrical energy in the formy of line wires.2] fonsupplying compressed air and electrical current for operating.;v the heater, i Trunnion 22,r comprising an outerbearing sleeve and an innerpipe-like portion, v,has a central. bore 28,.communicating with the end of they airfpipe 26.-L .One side of trunnion 42,2 has formed. therein a longitudinal channel; 29, .through `which the. electrical wiring ZIpasses upwardlyto the-heater.

.The heating unit ismounted on the upper end of ytrunnion 22 vvhichis provided, forthat purpose, with a nippleextension 3|] (Fig. 8). On the top of thetrunnion about extension 3l)A is -a cupshapedclosure 3| for thebottom of the heater housing .-Threadedly engaged with the extension 30 of the `spindle and .clamping the part 3l in place, is a Isleeve-like extension 32,.,depending from a disk-like base 33, for supporting several parts of the device. The bore of sleeve 32 opens upwardly through the top of base 33 which is formed about the opening with a slightly raised boss 34 for centering a portion of the housing for the heating element, which will now be described.

The housing forthe heating element comprises, preferably, a substantially cylindrical shell 35 molded with relatively thick walls from any known and suitable heat insulating material such, in the present instance, as one of the known asbestos compounds. The lower end of the shell is recessed for the reception of ak washer 36 by which it is supported on the base 33 and centered about its boss 34, as shown. The shell is held on the base by means of an enclosing metal sleeve or casing 31, the upper end of which has an inwardly turned flange 33 bearing against the upper end of the shell. The lower end of casing 31 is threadedly engaged with the periphery of base 33, so that it may be screwed down to rmly hold the shell 35 in place. The shell is centrally bored to provide a chamber 39 extending longitudinally therethrough and including an opening 40 in its upper end about which the shell is preferably provided with a projecting boss, as shown, by which the flange 38 of sleeve 35 is centered on the shell. Opening 46 serves as the upper opening in the shell through which the heated air is discharged, as hereafter described, and may be protected by a wire mesh screen 46a, as shown.

The heating element preferably comprises a core 4I of porcelain, or other suitable heat-resisting material, on which a coil 42 of the known electrical resistance Wire is spirally wound, as shown. The core, in the present instance, is closed internally, as by means of a transverse partition 43 (Fig. 8) and each end of the core is formed with a recess or socket 44 communicating with notches 45 in the ends of its side walls, for the reception of a metal spacing clip 46, having three or more arms 41 projecting outwardly through the notches 45, t a distance from the walls of the core, for spacing engagement with the inner walls of a sleeve 48 of porcelain, or other suitable heatresisting material, the sleeve, in turn, being fitted closely in the bore of the shell 35, as shown. The core 4l is thus centered on the boss 34 of base 33 with its end recess 44 communicating with a central opening 49 in the base through which air under pressure is supplied under control of a valve mechanism, which will now be described,

The valve means for controlling the supply of air to the heating element comprises, preferably, a hollow spool 53 (Fig. 8) slidably mounted in the opening 49 in the base. The central bore 5l of the spool communicates at its lower end with a number of eccentric branch outlets 52, leaving a central bridge portion 53. Portion 53 bears against the upper end of a spindle 54 of a valve mechanism mounted in the upper end of the bore 28 of trunnion 22. Valve spindle 54 slides in a. bearing in a thimble 55 threadedly and adjustably engaged in the upper end of bore 28. Fixed to the lower end of the thimble is a depending sleeve 56y the lower open end of which forms a valve port 51. Stem 54 extends downwardly below the lower end of sleeve 56 and has fixed thereon a cup-shaped valve member 58 containing a washer 59 of rubber, or other suitable yielding and resilient material, the upper surface of which is arranged for movement into and out of engagement with the lower end of sleeve 56, so as to act as a valve for the valve port 51. The walls of the cup 58 loosely overlap the lower end of the sleeve so as to admit air therebetween, from the trunnion bore 28, except when the valve body 59 is seated against the port 51 formed at the lower end of sleeve 56. A compression spring 60 is coiled about the valve stem between a shoulder 6I thereon and a shoulder 62 formed in the wall of sleeve 56,'the spring thus tending to normally raise the valve stem and closev the valve. A shoulder 63 on the valve stem bears loosely against sleeve 56 and guides the lower end of the spindle. The valve is shown in closed position in Figs. 6 and 8, and means are provided for moving spool 5U downwardly to depress the Valve spindleV 54 and open the valve, as indicated in Fig. '7, which means will now be described.

For operating the above described air valve and ythe circuit switch hereafter referred to, the heating unit is preferably provided with an outer metal housing which encloses and protects the inner insulating housing `and is mounted for movement relativethereto, This outer housing is shown at 64 (Figs. 6 and '1) as somewhat larger than and spaced from the casingv 31 of the inner housing. Three or more spaced rollers 65 are rotatably supported in the side walls of casing 31, adjacent its top,for spacing and guiding engagement with the outer housing 64. The top of the outer housing is formed with an inwardly curved flangel 66 to provide a smooth upper end and at its lower end it is extended to some distance below the inner housing and base 33, so as to overlap the iixed lower end 3| of the housing.

Below the base 33, the outer housing 64 has lixed thereto, as by means of screws 61, the several arms 68 of a frame or spider 69, shown in plan view in Figs. 3 and 9, Each arm 68 is hollow and its central bore 10 is reduced and threaded at its inner end, for thereception of a screw trunnion 1I, the inwardlyextended pointed end of which engages in a, circumferential groove 12 in spool 50. Each screw has a free vertical movement in a slot 13 in the depending sleeve'32 of .base 33, so that verticalmovement of the outer housing 64 is transmitted, through the spider and its trunnions 1I,Y to the 4spool 5U to depress it against the upper end of the valve spindle 54, to open the valve. The outer housing is depressed to open the valve by the pressure against its upper end of the tool, material container, or other article to be heated in the air current discharged through its upper opening 40, and upon release of the outer housing the parts are moved upwardly to close the air valve by the pressure of the valve spring 60. Y y.

The above described valve lmechanism mounted in the bore 28` is, in the present instance, a commercially available and well known type of valve unit commonly employed in vehicle tires, but it is evident that any other known and suitable valve unit may be substituted therefor having an operating part adapted to be actuated by spool 53. The valve stem 54 has a loose fit in thimble 55, to permit passage of the air, although it is evident that the thimble may be formed with other openings for the same purpose.;

The circuit including the heating element is controlled by a switch operated by the same movement of the outer housing 64 and of the spider 68 employed to control the air valve. For this purpose the base 33 has screwed to its under side a plate 14 of insulating material (Figs. 2, 3, 5 and 6), carrying binding posts, in the form of screws 15 and 16, to which are connected the wires 21 of the power line or other` source of electrical energy.

Supported on screws 76 also is an angular conducting metal plate 71, one end 18 of which is engaged in a recess in plate 14, to prevent rotation on the screw, while its opposite end 19 is turned horizontally and provided with a switch contact 88. The opposite side of plate Il is preferably protected by a sheet of rubber or other insulating material 8|. A cooperating switch contact B2 is xed in any suitable manner on a conducting metal plate 83 having its edges hanged inwardly to grip edge portions of a plate 84 of insulating material secured, as by screwsk 85 (Figs. 2, 4 and 5) to the under side of spider 69. Plate 83 is electrically connected in the circuit, as hereafter described, and it is evident from the above description that as outer housing 64 is lowered, the upper contact 82 is lowered into engagement with xed contact 88 on base 33, to close the circuit at approximately the same time as the operation of the valve for turning on the air supply.

The electrical circuit comprises the wires 21 of a power line or other source of energy, one of which wires leads, as described, to binding post 'l5 (Fig. 2). From this binding post a wire 86 is led upwardly through an insulated opening in base 33 and through one of the notches 45 in the lower end of the porcelain core 4I and longitudinally through the core to its upper end where it is led outwardly through one of the notches 45 and connected to the upper end of the resistance coil 42. The lower end of the resistance coil is connected with a wire 81 which passes through a side wall opening into the recess 44 at the bottom of the core from which it descends through another insulated opening in the base and it is looped as at 88, for flexibility. The lower end of the loop is electrically connected to the plate 83 carrying the contact 82 on the movable spider 69. It will be seen from this construction that depression of the outer housing 64 and the spider 69 operates to lower contact 82 into engagement with contact 88 and close the circuit including the heating element 42 and the source of electrical energy.

In operation, an instrument such as a dental cautery, or a container for rubber or other plastic material to be heated, may be pressed downwardly against the upwardly facing seat portion provided by the top flange 66 of the outer housing 64. By such pressure, the outer housing is slightly depressed from the positio-n shown in Fig. 6 to that of Fig. '7, with the result that the air valve is opened and the switch is operated to close the circuit and energize the heating element, as described. As the element is rapidly heated, a current of air is created upwardly abo-ut and in contact with the hot resistance element, with the result that a strong current of heated air is discharged upwardly through the registering upper openings in the inner and outer housings and into direct contact with the article to be heated. When the latter has acquired the desired temperature, it is removed from engagement with the outer housing which is elevated by the spring 60 of the valve, with the result that the valve is closed to cut off the air supply and the circuit is opened to deenergize theresistance coil. It will thus be seen that the device is semi-automatic and highly con- Venient in use, being operated solely by downward pressure thereon of the article to be heated as it is carried in the hand of the operator, so that no additional manipulation by the operator is required beyond the handling of the article itself. If desired, the heating element may be continuously energized, as by connecting the wire 81 to the binding post 16, but it has been found advantageous to include switch control of the circuit, since the described combination affords a very economical and satisfactory device, the operation of which is automatically conn-ed to the actual heating periods.

A modified embodiment, shown in Figs. l1 and l2, comprises, in addition to the main heating element described above, an auxiliary heating element of lower power consumption which is continuously energized to provide initial heating of the device and more rapid development of full heat. To this end, the insulating sleeve 48 described above is replaced by a sleeve 89 of porcelain or other suitable material and of reduced outer diameter so as to be spaced inwardly from the interior of shell 35, sleeve 89 being held in centered position by locating its lower end in a washer 90 which supports the shell 35 on the base 33, a washer of reduced inner diameter being employed to provide such spacing of the parts. An electrical resistance element Eil of known construction and lower power consumption than the main element A2, is coiled and supported on the sleeve 89 with its upper end connected with the circuit wire 86 leading to the upper end of the main coil 42. The lower end of auxiliary coil 9| is connected by a wire extending through one of the insulated openings in the base 33 described above and electrically connected to the binding post 16, below the switch contacts 88 and 82, so that auxiliary coil 9i is continuously energized to maintain the device continuously at a low temperature. In this modification the outer housing 92 is formed with double walls spaced from each other and enclosing asbestos or other suitable insulating material to retain the heat.

The electrical circuit for this modirication is shown in Fig. 12. The main heating element L32, for example, may have a rating of watts, while the auxiliary coil 9i may have a rating of 25 watts, but such ratings are subject, of course, to modication to suit different conditions and uses,

In the operation of the modification of Figs. ll and l2, the device is continuously heated to a low temperature by the auxiliary coil Si, so as t0 be already in a heated condition when an instrument or container` for material to be heated is pressed downwardly on the top of outer housing 92. Such depression of the housing as described above closes the circuit of the main heating element through the switch contacts 88 and 82 and opens the air switch, and the initial heating of the device and the presence of both heating coils enables it to more rapidly attain a full operating temperature. The low temperature maintained by the auxiliary coil is useful where only a low heating temperature is desired, and this modification thus enables the device to provide heat at two diierent temperatures.

The invention may thus be embodied in a relatively simple, compact device adapted to be substituted, for example, for the Bunsen burner commonly employed on dental equipment stands, conveniently occupying the same space and relative position adjacent the instrument table. The device is so constructed, furthermore, as to be readily and inexpensively manufactured and to be readily taken apart and reassembled for clean- .ing and repair in course of use.

It will thus be seen that the invention accomplishes its purposes, and while it has been herein described by reference to the particular details of a preferred embodiment, it is to be understood that such disclosure is intended in an illustra- 243 ifo-2o 7 tive, rather than a limiting sensei-f asit is'fcbr-itemplated that various'modifications and changes in the construction and arrangement of'the'parts will readily occur to those skilled in the art within the spirit of the invention and-the scope or" the appended claims.

1. An electrical heating device comprising a supporting base, a housing mounted on said base and having an air passage therethrough provided with inlet and outlet openings, means associated with said housing for movement upwardly yand downwardly and having an upwardly facing se'at portion locatedabove said outlet opening adapted to receive and hold an article .to bev heated, a source of air under pressure connected with said inlet opening, electrical heating means in said passage, a valve normally closing said-passage connections between said article receiving means and valve, and spring means for normally raising said receiving means and closing said valve, said receiving means being movable downwardly by the engagement with said seat portion thereof of an article to be heated, to openA said valve for heating said article.

2. An electrical heating device comprising inner and outer housings spaced from each other and having an air passage therethrough provided with inlet and outlet openings, one of said housings being movable upwardly and downwardly relative to the other and provided with an upwardly facing seat portion located above said outlet opening and adapted to receive and hold an article to be heated, a source of air under pressure connected with said inlet openings, electrical heating means in said passage, a valve normally closing said passage, a connection between the movable one of said housings and said valve, and spring means for normally raising said movable housing and closing said valve seat, said movable housing being movable downwardly by the engagement with said seat portion thereof of an article to be heated, to open said valve for heating said article.

3. An electrical heating device comprising inner and outer housings spaced from each other and having an air passage therethrough provided with inlet and outlet openings, said outer housing being mounted for movement upwardly and down'- wardly relatively to said inner housing and. having an upwardly facing seat portion located above said outlet opening and adapted to receive and hold an article to be heated, a source of air under pressure connected with said inlet opening, electrical heating means in said passage, a valve controlling said passage, a connection between said outer housing and valve, and spring means for normally moving said outer housing upwardly and closing said valve, said outer housing being arranged for downward movement to open said valve by the engagement with said seat lportion thereof of an article to be heated.

4. An electrical heating device comprising a supporting base, a housing movably mounted on said base and having an air passage therethrough provided with inlet and outlet openings, said housing having a portion located above said outlet opening thereof and formed to receive an article to be heated, a source of air under pressure connected with said inlet opening, an electrical resistance element in said passage for heating air passing therethrough, a valve controlling said passage, a connection between said housing and valve, and spring means for moving said housing in one direction and closing said valve,

8 said' housing being' movable in the oppbsi-te .direction toV open "said valve byfengagmentther'ewith 'of an article to be heatedf-in the ahi-diei charged from y'said opening. f1' 11" 5.' An electrical heating device comprising inner and outer housings spaced from -eachf'ovther and having an air'passage therethrough provided with inlet 'and outlet openings, oneof said housings being 'movable'relatively -to the other, a source of air under pressure connected with said inlet opening,Y an electrical resistance velement in `said passage'for heating the air passing therethrough; ar valve controlling said passage, a connection between said movable' housing and valve, and spring means for moving said movable housing in one direction and closing saidvalve, said movable housing being arranged for movement in' the op' posite direction"to open said valveby the lengagement therewith adjacent said outlet opening of an article to be heated in the current of air discharged from said opening.

6. An electrical heating device comprising an inner housing of heat insulating material, an outer housing spaced from and enclosing said inner housing and mounted for movement rela.- tively thereto, an air passage through said inner housing having an inlet opening, said housings having registering upper outlet openings, a sourceof air under pressure connected with said inlet opening, electrical heating means in said passage, a valve controlling said passage, a connection between said outer housing and valve, and spring means for raising said outer housing and closing said valve, said outer housing being arranged to be depressed to open said valve by the engagement therewith adjacent its outlet opening of an article to be heated in the current of air discharged therefrom.

7. An electrical heating device comprising an inner housing of heat insulating material, an outer housing spaced from and enclosing said innerhousing and mounted for movement relatively thereto, an air passage through said inner housing having an inlet opening for connection with a source of air vunder pressure, said housings having registering upper outlet openings, an electrical resistance coil inaccessibly enclosed in said passage for heating the air passing therethrough, a valve controlling said passage, a connectionV between said outer housing and valve, and spring means for raising said outer housing and closing said valve, said outer housing being movable downwardly to close said valve by downward pressure thereagainst adjacent said outlet opening by an article to be heated in the current of air discharged from said outlet opening,

v8. An electrical heating device comprising a .housing having an air passage therethrough provided with inlet and outlet openings, means movably associated with said housing having a .portion located above said outlet opening thereof and formed to receive an article to be heated, a source of air under pressure connected with said inlet opening, a valve for closing said passage, electrical heating means in said passage, a circuit including said heating means and a source of electrical energy, a switch controlling said circuit, connections between said article receiving means and said switch and valve, and spring means for raising said receiving means and opening said switch and closing said valve, said receiving means being movable downwardly by the engagement therewith of an article rto be heated to close said switch and open said valve.

9. An electrical heating device comprising a supporting base, a housing mounted for movement on said base and having an air passage therethrough provided with inlet and outlet openings, a source of air under pressure connected with said inlet opening, electrical heating means in said passage, a circuit including said heating means and a source of electrical energy, a switch controlling said circuit, a valve controlling said passage, connections between said housing and said switch and valve, and spring means for moving said housing in one direction and opening said switch and closing said valve, said housing being movable in the opposite direction to close said switch and open said valve by the engagement therewith adjacent said outlet opening of an article to be heated in the current of heated air discharged therefrom.

10. An electrical heating device comprising spaced inner and outer housings mounted for movement relatively to each other and having an air passage therethrough provided with inlet and outlet openings, a source of air under pressure connected with said inlet opening, electrical heating means in said passage, a circuit including said heating means and a source of electrical energy, a switch controlling said circuit, a Valve controlling said passage, a connection between the movable one of said housings and said switch and valve, and spring means for moving said movable housing in one direction to normally open said switch and close said valve, said movable housing being movable to close said switch and open said valve by the engagement therewith adjacent said outlet opening of an article to be heated in a current of heated air discharged from said opening.

11. An electrical heating device comprising spaced inner and outer housings having an air passage therethrough provided with inlet and outlet openings, said housings being movable relatively to one another, a source of air under pressure connected with said inlet opening, an electrical resistance element in said passage for heating the air passing therethrough, a circuit including said element and a source of electrical energy, a switch controlling said circuit, a valve controlling said passage, connections between the movable one of said housings and said switch and valve, and spring means for moving said movable housing in one direction to open said switch and close said valve, said movable housing being movable in the opposite direction to close said switch and open said valve by the engagement therewith of an article positioned at said outlet opening for heating by a current of air discharged therefrom,

12. An electrical heating device comprising an inner housing of heat insulating material, an outer housing enclosing and spaced from said inner housing and mounted for movement relative thereto, said housings having an air passage therethrough provided with inlet and outlet openings, a source of air under pressure connected with said inlet opening, an electrical resistance element in said passage for heating the air passing therethrough, a circuit including said element and a source of electrical energy, a switch controlling said circuit, a valve controlling said passage, connections between said outer housing and said switch and valve, and spring means normally raising said outer housing and opening said switch and closing said valve, said outer housing being arranged for depression to close said switch and open said Valve by downward pressure thereon adjacent said outlet opening by an article to be heated in the current of air discharged from said opening,

13. An electrical heating device comprising a stationary housing having an air passage therethrough provided with inlet and outlet openings, means movably associated with said housing having a :portion located above said outlet opening thereof and formed to receive an article to be heated, a valve normally closing said passage and having a connection with said receiving means, a pair of electrical heating elements inaccessibly enclosed in said passage, a source of electrical energy, circuit means connecting said source With one of said elements to normally heat the same, other circuit means connecting said source with the other of said elements and including a switch and a connection between said article receiving means and switch for actuating said switch, and spring means for normally moving said receiving means in one direction to open said switch and close said valve, said receiving means being movable in the opposite direction to close said switch and open said valve by the engagement therewith of an article to be heated.

14. An electrical heating device comprising a housing having an air passage therethrough provided with inlet and outlet openings, a source of air under pressure connected with said inlet opening, a spring actuated valve normally closing said passage, a pair of electrical heating elements in said passage, a source of electrical energy, circuit means connecting one of said elements with said source, other circuit means connecting the other of said elements with said source and including a switch, and means movably associated with said housing for closing said switch and opening said valve, said means being arranged for engagement and operation by an article positioned in .the current of heated air discharged from said outlet opening.

EDWARD J. RIES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 742,305 Garhart Oct. 27, 1903 1,252,614 Pieper et al. Jan. 8, 1918 1,386,616 Grandich Aug. 9, 1921 1,584,423 Bate May 11, 1926 1,949,658 Remseth et al. Mar- 6, 1934 1,950,626 Parks et al Mar. 13, 1934 2,085,470 Pieper June 29, 1937 2,090,371 Marks Aug. 17, 1937 2,343,453 Gillespie Mer, 7, 1944 FOREIGN PATENTS j Number Country Date 461,579 Greet Britain Feb. 19, 1937 

